1. Technical Field
This present disclosure relates to surgical devices which incorporate electro-surgical energy and gas plasmas. More specifically, the present disclosure relates to an improved apparatus and method for igniting the plasma.
2. Background of Related Aft
Surgical devices using gas plasma to conduct electrosurgical energy to a patient are well known in the art, as are techniques for igniting the gas plasma, and creating a plasma arc. Several of these techniques require creating a sufficiently strong electrical field that can ignite the plasma. One such technique is to move the tip of an electrode very close to the surgical site. The electric field along a path between the electrode and the surgical site increases as the separation between the electrode and the surgical site decreases. The electric field created between the electrode and the surgical site reaches a level sufficient to ignite the plasma. Another technique for igniting the gas plasma is to use a pointed electrode which generates a stronger electrical field at the tip, assisting in plasma ignition.
In yet another technique, a corona or corona discharge is created to ignite the plasma. As disclosed in U.S. Pat. No. 6,213,999, the entire disclosure of which is herein incorporated by reference, creating a corona discharge is achieved using a corona return electrode. The corona return electrode is located on the surgical handpiece and is electrically connected to the return potential of the electrosurgical generator. The corona return electrode is physically distinct from the electrosurgical return electrode although they are both electrically in circuit with the return potential of the electrosurgical generator. A dielectric barrier is required to prevent arcing between the active electrode and the corona return electrode. The dielectric barrier may also be used to prevent arcing between the ionized gas and the corona return electrode. A non-uniform electric field is generated between the corona return electrode and the active electrode. If sufficiently strong, this electric field causes a corona to form around the active electrode. The corona subsequently aids in the ignition of the plasma arc.
In each of the aforementioned techniques, a sufficiently strong electric field is necessary to ignite the gas. Once the gas is ignited and a plasma arc is formed a weaker electric field may maintain the plasma arc.